1987 Grand National, stock frame and no rolled lips Please HELP

[Chuck Leeper]

MT's site say 11.1 for section width...and in brackets it says 8. You're running a 9 inch...which I would think would increase your section width...which means you'll be closer to the frame and wheel lips.

ET Street® S/S

ET Street® S/S

www.mickeythompsontires.com

This thread is going nowhere fast....
First page: ". I dont know the back spacing on the gnx type wheels".
How about taking one off and measuring it. This isn't NASA calcs to do the moonshot.

 

[1986 Buick GX1]

I have a 15x8 wheel on the car now with a 4.75 backspacing and I have ½ inch clearance between tire and frame now.

My tire has a section with of 10.4 for my 255/50/16

The new tire has a with of 11.1 for a 275/60/15



We are going from a 15x8 with a 4.75 backspace to a wheel to a 15x9 with a 4.50 backspace.



Can you figure out what the clearance will be? I have racked my brain and I am burnt out.



Please help me out so I can stop over thinking this. I just can figure out what clearance I will have

This is the info I was hoping for.
I had assumed different wheels and my numbers were based off the wrong backspacing.
I’ll run the numbers and make a sketch when I get home tonight.
My initial thoughts are you will have more clearance at the frame and less clearance at the fender lip than your current setup. It should still be the same as hensleyt, only with a wider wheel.

 

[1986 Buick GX1]

I have a 15x8 wheel on the car now with a 4.75 backspacing and I have ½ inch clearance between tire and frame now.

My tire has a section with of 10.4 for my 255/50/16

The new tire has a with of 11.1 for a 275/60/15



We are going from a 15x8 with a 4.75 backspace to a wheel to a 15x9 with a 4.50 backspace.



Can you figure out what the clearance will be? I have racked my brain and I am burnt out.



Please help me out so I can stop over thinking this. I just can figure out what clearance I will have

Based off these numbers it should look something like this.
It would probably be a good idea to allow a 1/4” variation for sidewall bulge.
To measure for the fender lip you could jack the rear of the car up evenly, run a straight edge vertically on the outside of the tire and measure to the lip.
This should be a good visualization.